HIGH PERFORMANCECONCRETE

by

John J. Roller

CTLGroup

Early Louisiana HPC Research

Law & Rasoulian (1980)

Adelman & Cousins (1990)

Bruce, Russell & Roller – (1990-1993)

Law & Rasoulian (1980)

Concrete strengths of 6,500 psi and higher could be achieved using regionally available materials.

High strengths could best be achieved through use of crushed limestone aggregate.

Adelman & Cousins (1990)A mix design was developed that consistently yielded 28-day compressive strength in excess of 10,000 psi.

Measured MOR values compared well with results reported in other literature.

Measured MOE values represented the upper bound for the range of values reported in other literature.

Increasing design compressive strength from 6,000 psi to 10,000 psi resulted in an approximate 10% increase in span length and 5% decrease in superstructure cost.

Bruce, Russell & Roller (1990-93) With special attention to quality control, HPC with compressive strengths of 10,000 psi can be produced in a precast plant environment using regionally available materials.

HPC structural members performed in a manner that would be conservatively predicted using current AASHTO design provisions.

AASHTO provisions for estimating prestress loss due to creep and shrinkage may be too conservative for HPC with high compressive strengths.

Feasibility Study – RecommendationsUse of HPC with compressive strengths up to 10,000 psi should be considered by the Louisiana DOTD.

The effects of steam curing on the properties of high-strength HPC should be investigated further.

A HPC quality control training program should be developed for regional fabricators.

HPC with compressive strength up to 10,000 psi should be implemented in a bridge. This bridge should be instrumented.

Early Louisiana HPC Implementation

1988 – Specifying 8,000 psi concrete for a bridge project.

1992 – Successfully fabricating, shipping and driving a 130-ft long prestressed pile with concrete compressive strength of 10,450 psi.

1993 – Utilization of AASHTO Type IV girders with 8,500 psi compressive strength in Shreveport Inner Loop Expressway.

Implementation Project -Charenton Canal Bridge

(2001)

Charenton Canal Bridge - Section

Charenton Canal Bridge -Research Plan

Measure prestress force levels in selected strands during fabrication of girders for Span 3.

Measure concrete temperatures during initial curing of girders fabricated for Span 3.

Measure early-age and long-term concrete strains in girders and bridge deck slab for Span 3.

Measure early-age and long-term mid-span deflections for girders incorporated in Span 3.

Perform material property testing program for Span 3.

Charenton Canal Bridge -Conclusions

Reduction in prestress force occurring between the time of initial stress and release were greater than the PCI QC Manual tolerance and calculated steel relaxation prestress loss.

Concrete temperatures along the length of prestressed girders were not uniform during initial curing. In addition, curing temperatures measured in field-cured cylinders were considerably less than those measured in the girders. The consequence of this temperature variation was evident in the measured concrete compressive strengths.

Measured early-age and long-term prestress losses were considerably less than the design loss calculated using provisions of the AASHTO Standard Specification.

Measured early-age girder camber agreed well with the calculated design values. However, the calculated design values (with the appropriate PCI multipliers applied) did not provide a reliable estimate of long-term camber after the deck slab was cast.

Charenton Canal Bridge -Conclusions

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

0 12 24 36 48 60 72Time Since Pretensioning Strands, hours

Ave

rage

Str

and

Load

, lbf

ConcreteCastingCompleted

Steam Appliedfor Approx. 2.5Hours

StrandsReleased

StrandsTensioned

Measured Prestress Force

50

60

70

80

90

100

110

120

130

140

150

0 10 20 30 40 50

Time Since Casting Concrete, hours

Con

cret

e Te

mpe

ratu

re, °

F

Bottom Flange @ Mid-Span

Bottom Flange @ End

6 x 12 in. Cylinder

Temperature Variations

Compressive Strength

Concrete

Age,

Days

Initial

Curing

Method

Concrete

Compressive

Strength, psi

28Field 9,610

Match 10,570

90Field 10,670

Match 11,950

Prestress LossesPrestress

LossComponent

MeasuredLoss,

psi

DesignLoss,

psi

Elastic - ES 14,336 16,234

Relaxation - CRs - 1,805

Creep - CRc 18,589 25,686

Shrinkage - SH 5,750

Total 39,925 49,475

Girder Camber

Event(Time After

Release, days)

MeasuredCamber,

In.

CalculatedCamber,

In.

After Release (0.01) 1.00 1.41

Before Shipping (271) 2.40 2.51

After Casting Deck (303) 1.61 1.64

Final Reading (631) 1.58 0.87

Charenton Canal Bridge -Recommendations

Louisiana DOTD should continue specifying HPC on all bridges where its use is beneficial and economical.

When HPC is specified for a bridge, the Louisiana DOTD should consider conducting further research to investigate the early-age and long-term behavior of structural components. This objective could be accomplished by implementing instrumentation and testing programs similar to the one used for the Charenton Canal Bridge.

Fatigue & Shear Study (2000-2004) Tulane University; CTLGroup; HGR, Inc.

Provide assurance that 72-in. deep bulb-tee girders made with 10,000 psi compressive strength concrete will perform satisfactorily under fatigue and shear loading conditions.

Determine if a higher allowable concrete tensile stress can be used in design.

Investigate the use of welded-wire deformed shear reinforcement as an alternative to conventional bars.

Fatigue Endurance Tests

Test Matrix - Fatigue

SpecimenPeak

Extreme Fiber Tensile Stress, psi

Stress Range

Bottom Flange Status

Loading Frequency

BT6 6.0 HS-20 Pre-cracked 2.0 Hz

BT7 8.6 HL-93 Pre-cracked 1.9 Hz

BT8 7.5 HL-93 Pre-cracked 1.9 Hz

BT11 6.0 HL-93 Uncracked 1.0 Hz

BT12 7.5 HL-93 Uncracked 1.0 Hz

cf '

cf '

cf '

cf '

cf '

Fatigue Test Results

SpecimenBottom

Flange Status

Calculated Extreme Fiber Stress, psi *

Measured Steel

Stress Range, ksi

Fatigue Cycles

AchievedMax. Range

BT6 Pre-cracked 610 1,247 9.1 5,000,000

BT7 Pre-cracked 857 1,269 11.8 1,910,000

BT8 Pre-cracked 750 1,276 9.6 2,500,000

BT11 Uncracked 600 1,273 6.2 5,000,000

BT12 Uncracked 750 1,285 5.8 5,000,000

* Parameters calculated based on uncracked section properties.

Post-Fatigue Flexural Strength

Shear Strength Tests

Test Matrix - Shear

Specimen AASHTO Design

Deck Slab

Girder End

Test Region Reinforcement

BT6 Standard GGBFS (50%)

R No. 4 @ 10 in.

L D20 @ 12 in.

BT7 LRFDSilica Fume (5%)

R No. 4 @ 6.5 in.

L No. 4 @ 15 in.

BT8 LRFD Fly Ash (20%)

R D20 @ 8 in.

L D20 @ 12 in.

Shear Strength Test Results

0

100

200

300

400

500

600

700

BT6-L BT6-R BT7-L BT7-R BT8-L BT8-R

DesignMeasured

Test Specimen End

AppliedShear,kips

Fatigue & Shear Study -Conclusions

High-strength concrete girders incorporating mid-span flexural cracks can be expected to perform adequately under fatigue loading conditions when extreme fiber tensile stress is limited to the current allowable level.

Fatigue test results indicate that higher allowable tensile stresses for HPC can be used if the concrete remains uncracked. However, the potential for unanticipated cracking makes utilizing reserve strength a risky proposition.

Fatigue & Shear Study -Conclusions

Measured shear strengths for high-strength concrete girders exceeded the corresponding calculated strengths determined using current design provisions from either the AASHTO Standard Specifications or AASHTO LRFD Specifications.

The existing 60 ksi limit for the design yield strength of transverse reinforcement is conservative, and higher yield strength values can be conservatively utilized for deformed welded wire reinforcement.

Fatigue & Shear Study -Recommendations

The allowable concrete tensile stress used in flexural design of HPC girders should be limited to 6 .

The Louisiana DOTD may implement the use of 72-in. deep HPC bulb-tee girders designed in accordance with current AASHTO provisions with the knowledge that girder performance will be satisfactory.

Deformed welded wire reinforcement with a design yield strength of 75 ksi may be used as an alternative to conventional deformed bars.

cf '

- 62-Span Bridge- Total Length = 5,489 ft- HPC Incorporated in Two 131-ft Long Spans- HPC Spans Incorporate Four BT-78 Girders

Implementation Project –US 90 Rigolets Pass Bridge

(2007)

Overall Research Objective

Monitor the structural behavior of one of the two HPC spans in the Rigolets Pass Bridge for the purpose of obtaining additional data for the State’s growing HPC data base that will be useful in the development of specifications and designs for future HPC bridge structures.

Project Team

Tulane University

CTLGroup

Henry G. Russell, Inc.

Rigolets Pass Bridge –Research Plan

Measure prestress force levels in selected strands during fabrication of girders for Span 43.

Monitor early-age and long-term concrete strains in girders and bridge deck slab incorporated in Span 43.

Monitor early-age and long-term mid-span deflections for girders incorporated in Span 43.

Perform material property testing program for Span 43.

Install on-site automated data acquisition system with remote access capability and web-site presentation.

Instrumented Bridge Span(Span No. 43)

Design InformationStructural design per AASHTO Standard Specifications (Sixteenth Edition).

Design live load based on greater of MS-18 or HST-18(M).

Specified girder concrete compressive strength of 6,670 psi at release and 10,000 psi at 56 days.

Specified deck slab concrete compressive strength of 4,200 psi at 28 days.

Girder Fabrication Information

Girders fabricated by Gulf Coast PreStress, Pass Christian, Mississippi.

Each BT-78 HPC girder incorporated fifty-six 0.6-in. diameter, Grade 270, low-relaxation strands in lower flange.

Each strand in lower flange stressed to initial force of 43.95 kips (75% of specified minimum breaking strength).

GIRDERINSTRUMENTATION

& FABRICATION

Strand Load Cells

DEAD END VIEW

Vibrating Wire Strain Gages

DEAD END VIEW

Material Sampling

Camber Instrumentation

SPAN NO. 43CONSTRUCTION

Deck Slab VWSGs

Camber/Deflection Reference

Deck Concrete Placement

PRELIMINARY RESEARCH RESULTS

Girder Concrete Mix DesignMaterial Quantity per yd3

Portland Cement (Type III) 846 lbSilica Fume 100 lbFine Aggregate 1,149 lbCourse Aggregate - Limestone 1,866 lbWater 204 lbWater Reducer (ASTM C494, Type D) 38 ozHigh-Range Water Reducer (ASTM C494, Type F)

51 oz

Air Entrainment NoneWater/Cementitious Ratio 0.22

6,000

8,000

10,000

12,000

14,000

0 10 20 30 40 50 60 70 80 90 100

Concrete Age, days

ConcreteCompressive Strength, psi

Girder 43AGirder 43BGirder 43CGirder 43D

Girder Concrete Compressive Strength

MOE vs Compressive Strength

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000Compressive Strength, psi

ConcreteModulus

ofElasticity,

ksiAASHTO ExpressionPiles P1, P2, P3Girders BT1, BT2, BT3, BT5Charenton - MatchCharenton - FieldBT6, BT7, BT8BT11, BT12Girders 43A, 43B, 43C, 43D

MOR vs Compressive Strength

0

200

400

600

800

1,000

1,200

1,400

2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000Concrete Compressive Strength, psi

ConcreteModulus ofRupture, psi

Piles P1, P2, P3Girders BT1, BT2, BT3, BT5CharentonBT6, BT7, BT8Girders BT11, BT12Girders 43A, 43B, 43C, 43D

fr = 7.5 f 'c

fr = 10 f 'c

Creep Coefficient

0.00

0.50

1.00

1.50

2.00

2.50

3.00

0 100 200 300 400 500Concrete Age, days

CreepCoefficient

Age of Loading = 4 DaysAge of Loading = 100 days

Shrinkage

-50

0

50

100

150

200

250

300

350

400

0 100 200 300 400 500

Concrete Age, days

ConcreteShrinkage,

με

Age of Loading = 4 Days

Age of Loading = 100 days

Prestress Force Measurement

Girder Production

Run

Average Force After Stressing All

Strands

Average Force Prior to Release of

PrestressKips %

ReductionKips %

Reduction43 A and 43B 42.01 4.4 40.94 6.8

43C and 43D 41.80 4.9 40.04 8.9

Average 41.90 4.7 40.49 7.9

Specified 43.95 <5.0 - -

Measured Girder Concrete Strains

-200

0

200

400

600

800

1,000

1,200

0 100 200 300 400 500

Time Since Release, days

ConcreteStrain,με

Girder 43A-BF and TF Girder 43B-BF and TF

Girder 43C-BF and TF Girder 43D-BF and TF

Measured Prestress Loss

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

0 100 200 300 400 500

Time Since Release, days

PrestressLoss,

psi

Girder 43AGirder 43BGirder 43CGirder 43D

Prestress LossesPrestress

LossComponent

MeasuredLoss,

psi

DesignLoss,

psi

Elastic - ES 19,563 20,545

Relaxation - CRs - 908

Creep - CRc 6,720 34,993

Shrinkage - SH 5,750

Total 26,283 62,197

Measured Midspan Camber

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 100 200 300 400 500 600 700Time After Strand Release, days

MidspanCamber, in.

Girder 43A Girder 43B

Girder 43C Girder 43D

Girder CamberEvent

(Time AfterRelease, days)

MeasuredCamber,

In.

CalculatedCamber,

In.

After Release (0.01) 2.25 3.15

Before Shipping (110-118) 3.54 3.49

After Casting Deck (177-185) 1.86 1.93

6 Mo. After Deck Cast (364-372) 1.72 1.93

Final Reading (?) ? -

Measured Deck Slab Strain

-50

0

50

100

150

200

0 100 200 300 400 500 600

Time After Cast, days

CompressiveStrain @

Mid-Depth of Deck Slab,

με

43-S143-S243-S343-S443-S543-S643-S7

On-Site DAS w/Remote Access

Web-Based Data Posting

THANK YOU!